Ewaso Ng’iro North Catchment Area (ENNCA) – Nanyuki

The Ewaso Ng’iro North Catchment Area covers an area of about 210,226km2; it is about 36% of the total area of Kenya 576,000km2.

It’s the largest of all the six catchment areas but with least population, this is because it falls in Arid and Semi-Arid (ASAL) parts of Kenya.

The EwasoNg’iro North River drains the southern part of the catchment (5AA, 5AB, 5AC, 5AD, 5BA, 5BB, 5BC, 5BD, 5BE, 5D) in an easterly direction, from the highlands around Mt. Kenya, Aberdare ranges and Nyambene hills. The EwasoNg’iro North is the main river in this system and has the following tributaries: EwasoNarok, Likiudu, Liliaba, NgareNdare, Ngusishi, Timau, Sirimon, Teleswani, Ontulili, Likii, Nanyuki, Rongai, Burguret, NaroMoru, Isiolo, Moyok, Ngobit, Suguroi, Pesi and Mutara. The river flows into the Lorian swamp where it is an important source of water for recharging the groundwater and maintaining of vegetation cover.

The Daua and Chalbi system is part of the Ewaso Ngiro North Catchment Area. The Daua system is a perennial river that drains the north east tip of the catchment (5GB, 5HA, 5HD) and originates from the Ethiopian highlands and forms the border between the two countries before draining into Somali. Whereas the Chalbi system is an internal drainage lake that drains the north-west part of the catchment (sub-catchment 5J). It is a shallow lake which forms seasonally in response to rainfall (including some run-off from the Ethiopian highlands).